Ports are numbers ranging from 0 to 65535. Ports can be TCP or UDP.

POP3 110 
POP3 SSL 995 
IMAP 143 
IMAP SSL 993 
SMTP 25 
SMTP SSL 465 
HTTP 80 
HTTP SSL 443 
FTP 21 
FTPs 990 
SFTP 22 
MySQL 3306 
MSSQL 1433 
SSH 22